Our real world is a 3D world, and two-dimensional (2D) panel display and projection displays have lagged behind people's demand for the display technology. New technology that can objectively represent the 3D objects as in the real world is required. Different from traditional 2D display which can only display 2D information, 3D display adds image depths to generate stereo display. Comparing to traditional 2D display, 3D display adds information of image depths. Therefore, the major technical difficulty of 3D technology is the acquisition, processing, transmission and representation of the enormous amount of 3D data.
Current major 3D display technologies comprise: stereoscopic 3D display, autostereoscopic 3D display, holographic 3D display and space 3D display.
Stereoscopic 3D display is to allow the viewer's right and left eyes to receive the right and left image, respectively, through viewing aids such as glasses to achieve binocular parallax for the stereoscopic visual effect. Current popular 3D movies and videos on the market mostly adopt this method. This type of 3D display can provide visual effects of depth. However, due to the limit of two-view information, the viewer will see the same 3D scene from different positions, and the scene does not change when the viewer's position changes. In addition, this type of 3D presentation may cause negative effects to the viewers, such as headache and nausea, if viewed for a long time.
Autostereoscopic 3D display does not require viewing aids. It achieves 3D display for naked eyes with a limited number of view areas through providing separated viewing areas. This type of 3D display method provides a limited number of viewing angles at small watching areas, thus cannot satisfy people's demand for 3D display.
Holographic 3D display records the specific wavefront emitted by the object in the form of interference fringes and reconstructs it under a certain condition utilizing the light interference to form the 3D image of the original object. Holographic 3D display retains complete information of amplitudes and phases of the object wave, which allows the viewer to observe the visual effect that is completely the same as the original object, retaining all the depth cues. This is an ideal 3D display method. However, holographic 3D display requires enormous amount of information data, huge storage space and high quality spatial light modulator. For the time being, dynamically refreshing holographic 3D display generally is not possible.
Space 3D display comprises volumetric 3D display and omni-directional view 3D display.
Volumetric 3D display is to simulate the distribution of the 3D objects in the physical space, and display information of voxels in 3D space. Through displaying the scanned image of the voxels in the whole space while controlling the brightness of the voxels, 3D image display is realized. Although this 3D display method allows multiple persons to view with naked eyes, the 3D scene presented is transparent and space has no occlusion.
Omni-directional view 3D display is to represent corresponding object image in every direction in the whole space. This 3D display not only allows surrounding multiple persons to view the image in naked eyes, but also provides correct occlusion relationship. Generally, this 3D display has high-density view pitch, requiring enormous amount of data storage and transmission. The omni-directional view 3D display in the prior art is to display a cycle of discrete images sequence corresponding to the surrounding view points in the horizontal 360° direction. Through limiting the viewing angle of the image by the directional diffusing screen, each image is visible within the small scope close to its view point only, and the surrounding viewers will see different images that corresponding to their view points, realizing 3D effects. However, omni-directional view 3D display relies on various screens or display media, and the 3D scene in the prior art displays within the screen. With the screen, surrounding viewers will not be able to touch and interact, and therefore the sense of reality is not strong enough.